The present invention relates to a driver alert system for a vehicle, and more particularly to a driver alert system for a vehicle having adaptive cruise control.
Cruise control systems for automotive vehicles have been available for years. Typically, for the basic systems, the operator attains the desired vehicle speed and initiates the cruise control system. The vehicle then travels at the set speed unless the operator applies the brakes or turns off the system. With advances in electronics and sensor technology, adaptive cruise control (ACC) systems are becoming available that not only maintain the set vehicle speed, but also include a radar, laser or other type of sensing system, that will detect if the host vehicle is following too closely behind a preceding vehicle and automatically apply the vehicle brakes in order to increase this distance. If particularly close, then the system may also alert the operator of the condition. These types of systems typically use the distance between the vehicles (range), relative speed between the vehicles, and a preset time threshold to determine if an alert is desirable. However, these systems have tended to produce a significant amount of nuisance alerts, where the alert is activated when the relative conditions between the two vehicles does not really warrant the alert.
Thus, it is desirable to have a driver alert system that will accurately determine when a vehicle operator alert may be needed in a vehicle with an adaptive cruise control system.
In its embodiments, the present invention contemplates a driver alert system for alerting a host vehicle operator relative to a preceding vehicle, with the host vehicle having an adaptive cruise control system. The driver alert system has a plurality of inputs that receive a vehicle speed for the host vehicle, a relative speed between the host vehicle and the preceding vehicle, and a range between the host vehicle and the preceding vehicle. There is a requested braking determiner that calculates a first braking factor if the adaptive cruise control system is on and calculates a second braking factor if the adaptive cruise control system is off, and a delay determiner that calculates a first delay time to braking if the adaptive cruise control system is on and calculates a second delay time to braking if the adaptive cruise control system is off. A host vehicle deceleration predictor has inputs in communication with the requested braking determiner and the delay determiner. The driver alert system also includes a preceding vehicle deceleration determiner, and a range predictor that has inputs in communication with the host vehicle deceleration predictor, the preceding vehicle deceleration determiner, the relative speed between the host vehicle and the preceding vehicle, and the range between the host vehicle and the preceding vehicle. There is also an alert threshold generator, and an alert decision determiner that is in communication with the alert threshold generator and the range predictor.
The present invention further contemplates a method of detecting a driver alert situation for an operating host vehicle that precedes a preceding vehicle, the method comprising the steps of: determining a difference in speed between the host vehicle and the preceding vehicle; determining a difference in a rate of acceleration between the host vehicle and the preceding vehicle; determining a range between the host vehicle and the preceding vehicle; detecting if an adaptive cruise control system is on or off; determining an alert need, based upon the difference in speed and the difference in acceleration, if an adaptive cruise control deceleration is sufficient for the host vehicle to avoid the preceding vehicle if the adaptive cruise control system is on, and if a possible situation exists where the host vehicle will not avoid the preceding vehicle due to predicted inputs from a vehicle operator if the adaptive cruise control system is off; and providing a driver alert when the adaptive cruise control is detected as on and the adaptive cruise control deceleration is not sufficient for the host vehicle to avoid the preceding vehicle, and when the adaptive cruise control is detected as off and the possible situation exists that the host vehicle will not avoid the preceding vehicle.
An advantage of the present invention is that a host vehicle operator will be alerted by a driver alert system of particular situations regarding the adaptive cruise control braking relative to a preceding vehicle, if the ACC is on, and the host vehicle operator will be alerted to particular situations regarding the operator reaction time and braking relative to a preceding vehicle, if the ACC is off.
Another advantage of the present invention is that the driver alert system can alert the driver at different levels, such as visual and audible, based upon a system severity determination.
A further advantage of the present invention is that the driver alert system minimizes nuisance driver alerts that can occur.